In July 1971, at a dusty little stadium in India, a side representing the unrecognised nation of Bangladesh struck a meaningful blow for independence from Pakistan. This is their story.

On 25 July 1971, at a small stadium in India packed to its brim, a team from what was then East Pakistan played a side representing the Nadia district of West Bengal. Just before kick-off, the East Pakistan captain unfurled a green flag with a map of modern day Bangladesh at its centre. To the sound of applause and cheering from the 10,000-strong crowd, the flag was paraded around the perimeter of the pitch, then hoisted alongside the national colours of India.

In this dusty stadium in an inconspicuous corner of the world, the East Pakistan players had made history. This was the first time that the flag of Bangladesh – a country still not officially recognised – had been unfurled on foreign soil. As ambassadors of the war for liberation that was raging in East Pakistan, the Bangladesh XI – the country's first international football team – were rebels first and footballers second.

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In 1947, the last British forces and colonial administrators departed the Indian subcontinent. Behind them they left the new republic of India and the Islamic republic of Pakistan, the latter divided into East and West regions and flanking the Indian peninsula on both sides. Though long sought after, independence came at a high price. With the subcontinent split into two separate nations, the years before and after independence bore witness to a mass exodus of refugees travelling from one country to another, depending on their religion. As a result, pogroms, rioting and massacres erupted in the provinces of Bengal and the Punjab.

East Pakistan had a prickly relationship with its counterpart in the West. The enormous peninsula of India dividing the two regions spatially meant that, barring religion, the two regions had very little in common. The people of East Pakistan shared cultural and linguistic similarities with the bordering Indian states of West Bengal and Assam, rather than the Punjabi and Pashtun cultures of West Pakistan.

This cultural divide was further exacerbated by the fact that although East Pakistan had a larger population, it possessed little political influence in the capital city of Islamabad, located some 2,000 miles away in West Pakistan. The West also enjoyed the bulk of the common budget and deemed the Bengalis of the East to be inferior and not "martially inclined".

By the nineteen-seventies, a popular Bengali nationalist movement seeking greater autonomy had sprung up in East Pakistan, much to the dismay of General Yahya Khan, who had become the nation's president a year earlier. In March, Sheikh Mujibur Rahman, the leader of the Awami League, delivered an address that closed with the words: "Our struggle is for our freedom. Our struggle is for our independence."

On 25 March 1971, Islamabad ordered the commencement of Operation Searchlight, aimed at eliminating all opposition in East Pakistan, be it political, social or military. Over the next few months, this military action would lead to a systematic genocide of three million civilians, while around 10 million refugees fled to neighbouring India.

A provisional government was formed in Bangladesh, which later shifted its seat to Calcutta (now "Kolkata") in India as a government in exile. Covertly financed and trained in guerrilla warfare by the Indian armed forces and intelligence services in camps across the border, their military wing, the Mukti Bahini ("Liberation Army"), declared war on the occupying armed forces of Pakistan.

An independence march in Dhaka, with harpoons for added emphasis, in March 1971 // PA Images

The provisional government entrusted Shamsul Haq to form a sports association, the Bangladesh Krira Samity ("Bangladesh Sports Committee"). With the help of the committee's first secretary Lutfor Rahman, former footballer and coach Ali Imam, and former East End Club footballer Saidur Rahman Patel, Haq decided to form a football team who would act as ambassadors of the revolution and spread the word of independence.

Both All India Radio and the Shadhin Bangla Betaar Kendro broadcast a call to Bangladeshi footballers living in the refugee camps scattered across India to attend trials for the team. Coach Nani Bashak finally selected 25 players to meet for a special training camp before the squad began touring India, playing fundraising matches to support the Mukti Juddho ("Liberation War").

A few others linked up with the squad after the camp. Kazi Salahuddin, one of the most talented footballers Bangladesh has ever produced, had initially joined a guerrilla training camp to fight the war. It was there that a photojournalist from Calcutta told him about the football team. Already a star of Dhaka club Mohammedan Sporting, then the leading side in East Pakistan, Salahuddin immediately travelled to Calcutta in an Indian Air Force plane to join the team.

Thus was born the Shadhin Bangla Football Dol ("Free Bengal Football Team"). Zakaria Pintoo was appointed captain and Protap Shankar Hazra was made his deputy. Along with figures like Kazi Salahuddin, Nurunnabi, Saidur Rahman Patel, Ali Imam, Govinda Kundu, Amalesh Sen and Sheikh Ashraf Ali, they would go on to forge their place in Bangladesh's sporting and political history.

In late July, the team made its debut at the Krishnanagar Stadium in West Bengal, India. With the small stadium packed to capacity, people climbed trees and walls, or watched from the terraces of neighbouring houses. The hard-fought match, which ended in a 2-2 draw, was attended by representatives of the Bangladeshi government in exile, including Prime Minister Tajuddin Ahmed. It was in this game that the team unfurled the flag representing an independent Bangladesh.

"I still remember that day. It is the most memorable moment of my life being the first person to hoist the Bangladesh flag outside the country. It was also a historic moment for Bangladeshi football," Zakaria Pintoo recalled more than 40 years later in an interview with Daily Star, Bangladesh's leading English-language daily.

Hoisting the flag was a political act, and an extremely controversial one, being as India was still yet to recognise Bangladesh as an independent nation. The Indian officials had even sought to persuade the team not to go through with the gesture, but finally relented just before the match. The government was unhappy, however, and came down heavily on the District Magistrate of Nadia for fielding the official district team, suspending him from duty. Nadia also lost its place in the Indian Football Association for a year as punishment for hosting the Bangladeshi side.

Their next match was against the mighty Mohun Bagan of Calcutta, then one of Asia's best football sides. However, the controversy in the previous match meant that Bagan would play under the banner of Gostha Pal XI, in honour of a club legend and a giant of Indian football. Although the match was an easy 4-2 victory for Bagan, captain Chuni Goswami expressed great appreciation for the Bangladeshi side.

"The day I took over as the captain of Mohun Bagan, I desired to do something for the freedom movement...With all our support for the game, we stood next to them in the freedom struggle," he said after the match.

On 14 August, Pakistan's independence day, the team beat a Calcutta XI 4-2. Prior to kick-off, in an act meant to humiliate Islamabad, the Bangladeshi footballers trampled on the Pakistani flag, set it ablaze and threw it into the stands – much to the dismay of the Indian government.

But, according to Kausik Bandopadhyay, historian and author of Bangladesh Playing: Sport, Culture and Nation, the match that attracted the most attention was against Sports Week XI in Bombay. Khalid Ansari, the editor of Sports Week, was instrumental in organising the match. Dashing cricketer Mansour Ali Khan Pataudi captained the Indian side and even managed to score a goal.

The Bangladeshi team won the game 3-1, after which Pataudi, along with the Governor of Bombay and Bollywood star Dilip Kumar, contributed huge amounts to the Bangladesh Relief Fund. Around £1,800 was collected from the sale of tickets alone, and this too went to the fund.

The team played its last match against a Balurghat XI in West Bengal. It was a highly emotional occasion as a guerrilla training camp was located in Balurghat and members of the team met liberation fighters in person before their game.

On 3 December 1971, Pakistan Air Force launched a pre-emptive strike on 11 airfields across northern India. That evening, Indian Prime Minister Indira Gandhi declared war against Pakistan. Within two weeks the Pakistani forces fell; they officially surrendered on the afternoon of 16 December 1971.

Pakistani lieutenant generals sign the surrender agreement as Indian officers watch over them // PA Images

The Bangladesh XI was about to depart for Delhi to play another fundraising exhibition match when they finally received the news they had been waiting for: Bangladesh was an independent nation. The team played a total of 16 matches in India – winning 12, losing three and drawing one – and also managed to collect funds amounting to 500,000 Bangladeshi taka, a significant amount in those days.

Back home, they were greeted as ambassadors of the revolution. Most went on to play at domestic and international level, while many of them won awards and have been recognised by the Bangladeshi government for their service to the cause of liberation. Outside Bangladesh, however, very few know of their story.